<!DOCTYPE html>
<html lang="zh-CN">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title></title>
  </head>
  <body>
    <div id="app">
      <button @click=say>点击</button>
      <div ref="box"></div>
    </div>
    <script src="./vue.js"></script>
    <script>
      const vm=new Vue({
        el:'#app',
        data:{},
        methods:{
          say(){
          this.$refs.box.innerHTML="🐱"

        }},
       })
    </script>
  </body>
</html>